OAKLAND, CA - AUGUST 10:  Independent presidential candidate U.S. Sen. Bernie Sanders (I-VT) greets nurses as he arrives at a "Brunch with Bernie" campaign rally at the National Nurses United offices on August 10, 2015 in Oakland, California.  The National Nurses United members announced their endorsement for independent presedential hopeful Sen. Bernie Sanders during a campaign stop before he heads to Los Angeles for a campaign rally in Los Angeles at the Memorial Sports Arena.  (Photo by Justin Sullivan/Getty Images)